* [PATCH] watchdog: stm32: add dynamic prescaler support @ 2019-04-26 13:41 Ludovic Barre 2019-04-26 14:16 ` Guenter Roeck 0 siblings, 1 reply; 4+ messages in thread From: Ludovic Barre @ 2019-04-26 13:41 UTC (permalink / raw) To: Wim Van Sebroeck, Guenter Roeck, Rob Herring Cc: Maxime Coquelin, Alexandre Torgue, linux-watchdog, linux-arm-kernel, linux-kernel, devicetree, linux-stm32, Ludovic Barre From: Ludovic Barre <ludovic.barre@st.com> This patch allows to define the max prescaler by compatible. To set a large range of timeout, the prescaler should be set dynamically (from the timeout request) to improve the resolution in order to have a timeout close to the expected value. Signed-off-by: Ludovic Barre <ludovic.barre@st.com> --- drivers/watchdog/stm32_iwdg.c | 70 +++++++++++++++++++++++++------------------ 1 file changed, 41 insertions(+), 29 deletions(-) diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c index e00e3b3..91d0a89 100644 --- a/drivers/watchdog/stm32_iwdg.c +++ b/drivers/watchdog/stm32_iwdg.c @@ -34,18 +34,10 @@ #define KR_KEY_EWA 0x5555 /* write access enable */ #define KR_KEY_DWA 0x0000 /* write access disable */ -/* IWDG_PR register bit values */ -#define PR_4 0x00 /* prescaler set to 4 */ -#define PR_8 0x01 /* prescaler set to 8 */ -#define PR_16 0x02 /* prescaler set to 16 */ -#define PR_32 0x03 /* prescaler set to 32 */ -#define PR_64 0x04 /* prescaler set to 64 */ -#define PR_128 0x05 /* prescaler set to 128 */ -#define PR_256 0x06 /* prescaler set to 256 */ +#define PR_SHIFT 2 /* IWDG_RLR register values */ -#define RLR_MIN 0x07C /* min value supported by reload register */ -#define RLR_MAX 0xFFF /* max value supported by reload register */ +#define RLR_MAX GENMASK(11, 0) /* max value of reload register */ /* IWDG_SR register bit mask */ #define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ @@ -55,15 +47,28 @@ #define TIMEOUT_US 100000 #define SLEEP_US 1000 -#define HAS_PCLK true +struct stm32_iwdg_data { + bool has_pclk; + u32 max_prescaler; +}; + +static const struct stm32_iwdg_data stm32_iwdg_data = { + .has_pclk = false, + .max_prescaler = 256, +}; + +static const struct stm32_iwdg_data stm32mp1_iwdg_data = { + .has_pclk = true, + .max_prescaler = 1024, +}; struct stm32_iwdg { struct watchdog_device wdd; + const struct stm32_iwdg_data *data; void __iomem *regs; struct clk *clk_lsi; struct clk *clk_pclk; unsigned int rate; - bool has_pclk; }; static inline u32 reg_read(void __iomem *base, u32 reg) @@ -80,21 +85,30 @@ static int stm32_iwdg_start(struct watchdog_device *wdd) { struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); u32 val = FLAG_PVU | FLAG_RVU; - u32 reload; + u32 timeout, presc, iwdg_rlr, iwdg_pr; int ret; dev_dbg(wdd->parent, "%s\n", __func__); - /* prescaler fixed to 256 */ - reload = clamp_t(unsigned int, ((wdd->timeout * wdt->rate) / 256) - 1, - RLR_MIN, RLR_MAX); + timeout = clamp_t(unsigned int, wdd->timeout, + wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); + + if (timeout != wdd->timeout) + dev_warn(wdd->parent, "timeout skrinked to %d\n", timeout); + + presc = DIV_ROUND_UP(timeout * wdt->rate, RLR_MAX + 1); + + /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ + presc = roundup_pow_of_two(presc); + iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; + iwdg_rlr = ((timeout * wdt->rate) / presc) - 1; /* enable write access */ reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); /* set prescaler & reload registers */ - reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ - reg_write(wdt->regs, IWDG_RLR, reload); + reg_write(wdt->regs, IWDG_PR, iwdg_pr); + reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); /* wait for the registers to be updated (max 100ms) */ @@ -150,7 +164,7 @@ static int stm32_iwdg_clk_init(struct platform_device *pdev, } /* optional peripheral clock */ - if (wdt->has_pclk) { + if (wdt->data->has_pclk) { wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk"); if (IS_ERR(wdt->clk_pclk)) { dev_err(&pdev->dev, "Unable to get pclk clock\n"); @@ -191,8 +205,8 @@ static const struct watchdog_ops stm32_iwdg_ops = { }; static const struct of_device_id stm32_iwdg_of_match[] = { - { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK }, - { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK }, + { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, + { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, { /* end node */ } }; MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); @@ -200,20 +214,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); static int stm32_iwdg_probe(struct platform_device *pdev) { struct watchdog_device *wdd; - const struct of_device_id *match; struct stm32_iwdg *wdt; struct resource *res; int ret; - match = of_match_device(stm32_iwdg_of_match, &pdev->dev); - if (!match) - return -ENODEV; - wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); if (!wdt) return -ENOMEM; - wdt->has_pclk = match->data; + wdt->data = of_device_get_match_data(&pdev->dev); + if (!wdt->data) + return -ENODEV; /* This is the timer base. */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); @@ -231,8 +242,9 @@ static int stm32_iwdg_probe(struct platform_device *pdev) wdd = &wdt->wdd; wdd->info = &stm32_iwdg_info; wdd->ops = &stm32_iwdg_ops; - wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate; - wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate; + wdd->min_timeout = 1; + wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * + 1000) / wdt->rate; wdd->parent = &pdev->dev; watchdog_set_drvdata(wdd, wdt); -- 2.7.4 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] watchdog: stm32: add dynamic prescaler support 2019-04-26 13:41 [PATCH] watchdog: stm32: add dynamic prescaler support Ludovic Barre @ 2019-04-26 14:16 ` Guenter Roeck 2019-04-29 13:51 ` Ludovic BARRE 0 siblings, 1 reply; 4+ messages in thread From: Guenter Roeck @ 2019-04-26 14:16 UTC (permalink / raw) To: Ludovic Barre Cc: Wim Van Sebroeck, Rob Herring, Maxime Coquelin, Alexandre Torgue, linux-watchdog, linux-arm-kernel, linux-kernel, devicetree, linux-stm32 On Fri, Apr 26, 2019 at 03:41:15PM +0200, Ludovic Barre wrote: > From: Ludovic Barre <ludovic.barre@st.com> > > This patch allows to define the max prescaler by compatible. > To set a large range of timeout, the prescaler should be set > dynamically (from the timeout request) to improve the resolution > in order to have a timeout close to the expected value. > > Signed-off-by: Ludovic Barre <ludovic.barre@st.com> > --- > drivers/watchdog/stm32_iwdg.c | 70 +++++++++++++++++++++++++------------------ > 1 file changed, 41 insertions(+), 29 deletions(-) > > diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c > index e00e3b3..91d0a89 100644 > --- a/drivers/watchdog/stm32_iwdg.c > +++ b/drivers/watchdog/stm32_iwdg.c > @@ -34,18 +34,10 @@ > #define KR_KEY_EWA 0x5555 /* write access enable */ > #define KR_KEY_DWA 0x0000 /* write access disable */ > > -/* IWDG_PR register bit values */ > -#define PR_4 0x00 /* prescaler set to 4 */ > -#define PR_8 0x01 /* prescaler set to 8 */ > -#define PR_16 0x02 /* prescaler set to 16 */ > -#define PR_32 0x03 /* prescaler set to 32 */ > -#define PR_64 0x04 /* prescaler set to 64 */ > -#define PR_128 0x05 /* prescaler set to 128 */ > -#define PR_256 0x06 /* prescaler set to 256 */ > +#define PR_SHIFT 2 > > /* IWDG_RLR register values */ > -#define RLR_MIN 0x07C /* min value supported by reload register */ > -#define RLR_MAX 0xFFF /* max value supported by reload register */ > +#define RLR_MAX GENMASK(11, 0) /* max value of reload register */ > > /* IWDG_SR register bit mask */ > #define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ > @@ -55,15 +47,28 @@ > #define TIMEOUT_US 100000 > #define SLEEP_US 1000 > > -#define HAS_PCLK true > +struct stm32_iwdg_data { > + bool has_pclk; > + u32 max_prescaler; > +}; > + > +static const struct stm32_iwdg_data stm32_iwdg_data = { > + .has_pclk = false, > + .max_prescaler = 256, > +}; > + > +static const struct stm32_iwdg_data stm32mp1_iwdg_data = { > + .has_pclk = true, > + .max_prescaler = 1024, > +}; > > struct stm32_iwdg { > struct watchdog_device wdd; > + const struct stm32_iwdg_data *data; > void __iomem *regs; > struct clk *clk_lsi; > struct clk *clk_pclk; > unsigned int rate; > - bool has_pclk; > }; > > static inline u32 reg_read(void __iomem *base, u32 reg) > @@ -80,21 +85,30 @@ static int stm32_iwdg_start(struct watchdog_device *wdd) > { > struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); > u32 val = FLAG_PVU | FLAG_RVU; > - u32 reload; > + u32 timeout, presc, iwdg_rlr, iwdg_pr; > int ret; > > dev_dbg(wdd->parent, "%s\n", __func__); > > - /* prescaler fixed to 256 */ > - reload = clamp_t(unsigned int, ((wdd->timeout * wdt->rate) / 256) - 1, > - RLR_MIN, RLR_MAX); > + timeout = clamp_t(unsigned int, wdd->timeout, > + wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); > + > + if (timeout != wdd->timeout) > + dev_warn(wdd->parent, "timeout skrinked to %d\n", timeout); > + Valid values for timeout should be set in the set_timeout function, not here. As such, there is no need for this warning. More specifically, if the selected timeout is between min_timeout and max_hw_heartbeat_ms, and the hardware can not meet the exact requested value, the set_timeout function should adjust wdd->timeout value accordingly. Example: The requested timeout is 55 seconds, but the hardware can only support either 32 or 64 seconds. The set_timeout function should then set wdd->timeout to either 32 or 64. Furthermore, this is a valid condition. For example, the timeout could be set for one hour (or day), and the maximum heartbeat could be one minute. In that situation, the watchdog core handles heartbeat/ping requests. Again, this does not warrant a warning. On top of all that, if the hardware can not set a minimum timeout of 1 second, min_timeout should not be set to 1 second. It should be set to the actual minimum supportable value if that value is larger than 1 second. > + presc = DIV_ROUND_UP(timeout * wdt->rate, RLR_MAX + 1); > + > + /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ > + presc = roundup_pow_of_two(presc); > + iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; > + iwdg_rlr = ((timeout * wdt->rate) / presc) - 1; > > /* enable write access */ > reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); > > /* set prescaler & reload registers */ > - reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ > - reg_write(wdt->regs, IWDG_RLR, reload); > + reg_write(wdt->regs, IWDG_PR, iwdg_pr); > + reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); > reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); > > /* wait for the registers to be updated (max 100ms) */ > @@ -150,7 +164,7 @@ static int stm32_iwdg_clk_init(struct platform_device *pdev, > } > > /* optional peripheral clock */ > - if (wdt->has_pclk) { > + if (wdt->data->has_pclk) { > wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk"); > if (IS_ERR(wdt->clk_pclk)) { > dev_err(&pdev->dev, "Unable to get pclk clock\n"); > @@ -191,8 +205,8 @@ static const struct watchdog_ops stm32_iwdg_ops = { > }; > > static const struct of_device_id stm32_iwdg_of_match[] = { > - { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK }, > - { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK }, > + { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, > + { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, > { /* end node */ } > }; > MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); > @@ -200,20 +214,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); > static int stm32_iwdg_probe(struct platform_device *pdev) > { > struct watchdog_device *wdd; > - const struct of_device_id *match; > struct stm32_iwdg *wdt; > struct resource *res; > int ret; > > - match = of_match_device(stm32_iwdg_of_match, &pdev->dev); > - if (!match) > - return -ENODEV; > - > wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); > if (!wdt) > return -ENOMEM; > > - wdt->has_pclk = match->data; > + wdt->data = of_device_get_match_data(&pdev->dev); > + if (!wdt->data) > + return -ENODEV; > > /* This is the timer base. */ > res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > @@ -231,8 +242,9 @@ static int stm32_iwdg_probe(struct platform_device *pdev) > wdd = &wdt->wdd; > wdd->info = &stm32_iwdg_info; > wdd->ops = &stm32_iwdg_ops; > - wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate; > - wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate; > + wdd->min_timeout = 1; Is this guaranteed to be no larger than 1 under all circumstances ? [ Not that the old code was necessarily correct - it might have set min_timeout to 0 if wdt->rate is high ] > + wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * > + 1000) / wdt->rate; > wdd->parent = &pdev->dev; > > watchdog_set_drvdata(wdd, wdt); > -- > 2.7.4 > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] watchdog: stm32: add dynamic prescaler support 2019-04-26 14:16 ` Guenter Roeck @ 2019-04-29 13:51 ` Ludovic BARRE 2019-04-29 14:03 ` Guenter Roeck 0 siblings, 1 reply; 4+ messages in thread From: Ludovic BARRE @ 2019-04-29 13:51 UTC (permalink / raw) To: Guenter Roeck Cc: Wim Van Sebroeck, Rob Herring, Maxime Coquelin, Alexandre Torgue, linux-watchdog, linux-arm-kernel, linux-kernel, devicetree, linux-stm32 Hi Guenter On 4/26/19 4:16 PM, Guenter Roeck wrote: > On Fri, Apr 26, 2019 at 03:41:15PM +0200, Ludovic Barre wrote: >> From: Ludovic Barre <ludovic.barre@st.com> >> >> This patch allows to define the max prescaler by compatible. >> To set a large range of timeout, the prescaler should be set >> dynamically (from the timeout request) to improve the resolution >> in order to have a timeout close to the expected value. >> >> Signed-off-by: Ludovic Barre <ludovic.barre@st.com> >> --- >> drivers/watchdog/stm32_iwdg.c | 70 +++++++++++++++++++++++++------------------ >> 1 file changed, 41 insertions(+), 29 deletions(-) >> >> diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c >> index e00e3b3..91d0a89 100644 >> --- a/drivers/watchdog/stm32_iwdg.c >> +++ b/drivers/watchdog/stm32_iwdg.c >> @@ -34,18 +34,10 @@ >> #define KR_KEY_EWA 0x5555 /* write access enable */ >> #define KR_KEY_DWA 0x0000 /* write access disable */ >> >> -/* IWDG_PR register bit values */ >> -#define PR_4 0x00 /* prescaler set to 4 */ >> -#define PR_8 0x01 /* prescaler set to 8 */ >> -#define PR_16 0x02 /* prescaler set to 16 */ >> -#define PR_32 0x03 /* prescaler set to 32 */ >> -#define PR_64 0x04 /* prescaler set to 64 */ >> -#define PR_128 0x05 /* prescaler set to 128 */ >> -#define PR_256 0x06 /* prescaler set to 256 */ >> +#define PR_SHIFT 2 >> >> /* IWDG_RLR register values */ >> -#define RLR_MIN 0x07C /* min value supported by reload register */ >> -#define RLR_MAX 0xFFF /* max value supported by reload register */ >> +#define RLR_MAX GENMASK(11, 0) /* max value of reload register */ >> >> /* IWDG_SR register bit mask */ >> #define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ >> @@ -55,15 +47,28 @@ >> #define TIMEOUT_US 100000 >> #define SLEEP_US 1000 >> >> -#define HAS_PCLK true >> +struct stm32_iwdg_data { >> + bool has_pclk; >> + u32 max_prescaler; >> +}; >> + >> +static const struct stm32_iwdg_data stm32_iwdg_data = { >> + .has_pclk = false, >> + .max_prescaler = 256, >> +}; >> + >> +static const struct stm32_iwdg_data stm32mp1_iwdg_data = { >> + .has_pclk = true, >> + .max_prescaler = 1024, >> +}; >> >> struct stm32_iwdg { >> struct watchdog_device wdd; >> + const struct stm32_iwdg_data *data; >> void __iomem *regs; >> struct clk *clk_lsi; >> struct clk *clk_pclk; >> unsigned int rate; >> - bool has_pclk; >> }; >> >> static inline u32 reg_read(void __iomem *base, u32 reg) >> @@ -80,21 +85,30 @@ static int stm32_iwdg_start(struct watchdog_device *wdd) >> { >> struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); >> u32 val = FLAG_PVU | FLAG_RVU; >> - u32 reload; >> + u32 timeout, presc, iwdg_rlr, iwdg_pr; >> int ret; >> >> dev_dbg(wdd->parent, "%s\n", __func__); >> >> - /* prescaler fixed to 256 */ >> - reload = clamp_t(unsigned int, ((wdd->timeout * wdt->rate) / 256) - 1, >> - RLR_MIN, RLR_MAX); >> + timeout = clamp_t(unsigned int, wdd->timeout, >> + wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); >> + >> + if (timeout != wdd->timeout) >> + dev_warn(wdd->parent, "timeout skrinked to %d\n", timeout); >> + > > Valid values for timeout should be set in the set_timeout function, > not here. As such, there is no need for this warning. More specifically, > if the selected timeout is between min_timeout and max_hw_heartbeat_ms, > and the hardware can not meet the exact requested value, the set_timeout > function should adjust wdd->timeout value accordingly. > Ok, so I will adjust the timeout (with prescaler and reload look-up) value in set_timeout function. thanks > Example: The requested timeout is 55 seconds, but the hardware can > only support either 32 or 64 seconds. The set_timeout function should > then set wdd->timeout to either 32 or 64. > > Furthermore, this is a valid condition. For example, the timeout could > be set for one hour (or day), and the maximum heartbeat could be one > minute. In that situation, the watchdog core handles heartbeat/ping > requests. Again, this does not warrant a warning. > > On top of all that, if the hardware can not set a minimum timeout of > 1 second, min_timeout should not be set to 1 second. It should be set > to the actual minimum supportable value if that value is larger than > 1 second. > >> + presc = DIV_ROUND_UP(timeout * wdt->rate, RLR_MAX + 1); >> + >> + /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ >> + presc = roundup_pow_of_two(presc); >> + iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; >> + iwdg_rlr = ((timeout * wdt->rate) / presc) - 1; >> >> /* enable write access */ >> reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); >> >> /* set prescaler & reload registers */ >> - reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ >> - reg_write(wdt->regs, IWDG_RLR, reload); >> + reg_write(wdt->regs, IWDG_PR, iwdg_pr); >> + reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); >> reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); >> >> /* wait for the registers to be updated (max 100ms) */ >> @@ -150,7 +164,7 @@ static int stm32_iwdg_clk_init(struct platform_device *pdev, >> } >> >> /* optional peripheral clock */ >> - if (wdt->has_pclk) { >> + if (wdt->data->has_pclk) { >> wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk"); >> if (IS_ERR(wdt->clk_pclk)) { >> dev_err(&pdev->dev, "Unable to get pclk clock\n"); >> @@ -191,8 +205,8 @@ static const struct watchdog_ops stm32_iwdg_ops = { >> }; >> >> static const struct of_device_id stm32_iwdg_of_match[] = { >> - { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK }, >> - { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK }, >> + { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, >> + { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, >> { /* end node */ } >> }; >> MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); >> @@ -200,20 +214,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); >> static int stm32_iwdg_probe(struct platform_device *pdev) >> { >> struct watchdog_device *wdd; >> - const struct of_device_id *match; >> struct stm32_iwdg *wdt; >> struct resource *res; >> int ret; >> >> - match = of_match_device(stm32_iwdg_of_match, &pdev->dev); >> - if (!match) >> - return -ENODEV; >> - >> wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); >> if (!wdt) >> return -ENOMEM; >> >> - wdt->has_pclk = match->data; >> + wdt->data = of_device_get_match_data(&pdev->dev); >> + if (!wdt->data) >> + return -ENODEV; >> >> /* This is the timer base. */ >> res = platform_get_resource(pdev, IORESOURCE_MEM, 0); >> @@ -231,8 +242,9 @@ static int stm32_iwdg_probe(struct platform_device *pdev) >> wdd = &wdt->wdd; >> wdd->info = &stm32_iwdg_info; >> wdd->ops = &stm32_iwdg_ops; >> - wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate; >> - wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate; >> + wdd->min_timeout = 1; > > Is this guaranteed to be no larger than 1 under all circumstances ? > > [ Not that the old code was necessarily correct - it might have set > min_timeout to 0 if wdt->rate is high ] Infact, for not guaranteed the min timeout at 1s, the input clock (wdt->rate) should be < at 12Hz. On ST micro controller/processor the wdt->rate is based on LSI (Low Speed Internal) clock which is defined around 32KHz-39KHz I wanted avoid to set 0, due to min_timeout definition ("unsigned int" in struct watchdog_device) and comparator used in watchdog_timeout_invalid function. if the calculated value is < 1 => I could set 1, else I round on UP or Down value? Regards, Ludo > >> + wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * >> + 1000) / wdt->rate; >> wdd->parent = &pdev->dev; >> >> watchdog_set_drvdata(wdd, wdt); >> -- >> 2.7.4 >> ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] watchdog: stm32: add dynamic prescaler support 2019-04-29 13:51 ` Ludovic BARRE @ 2019-04-29 14:03 ` Guenter Roeck 0 siblings, 0 replies; 4+ messages in thread From: Guenter Roeck @ 2019-04-29 14:03 UTC (permalink / raw) To: Ludovic BARRE Cc: Wim Van Sebroeck, Rob Herring, Maxime Coquelin, Alexandre Torgue, linux-watchdog, linux-arm-kernel, linux-kernel, devicetree, linux-stm32 On 4/29/19 6:51 AM, Ludovic BARRE wrote: > Hi Guenter > > On 4/26/19 4:16 PM, Guenter Roeck wrote: >> On Fri, Apr 26, 2019 at 03:41:15PM +0200, Ludovic Barre wrote: >>> From: Ludovic Barre <ludovic.barre@st.com> >>> >>> This patch allows to define the max prescaler by compatible. >>> To set a large range of timeout, the prescaler should be set >>> dynamically (from the timeout request) to improve the resolution >>> in order to have a timeout close to the expected value. >>> >>> Signed-off-by: Ludovic Barre <ludovic.barre@st.com> >>> --- >>> drivers/watchdog/stm32_iwdg.c | 70 +++++++++++++++++++++++++------------------ >>> 1 file changed, 41 insertions(+), 29 deletions(-) >>> >>> diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c >>> index e00e3b3..91d0a89 100644 >>> --- a/drivers/watchdog/stm32_iwdg.c >>> +++ b/drivers/watchdog/stm32_iwdg.c >>> @@ -34,18 +34,10 @@ >>> #define KR_KEY_EWA 0x5555 /* write access enable */ >>> #define KR_KEY_DWA 0x0000 /* write access disable */ >>> -/* IWDG_PR register bit values */ >>> -#define PR_4 0x00 /* prescaler set to 4 */ >>> -#define PR_8 0x01 /* prescaler set to 8 */ >>> -#define PR_16 0x02 /* prescaler set to 16 */ >>> -#define PR_32 0x03 /* prescaler set to 32 */ >>> -#define PR_64 0x04 /* prescaler set to 64 */ >>> -#define PR_128 0x05 /* prescaler set to 128 */ >>> -#define PR_256 0x06 /* prescaler set to 256 */ >>> +#define PR_SHIFT 2 >>> /* IWDG_RLR register values */ >>> -#define RLR_MIN 0x07C /* min value supported by reload register */ >>> -#define RLR_MAX 0xFFF /* max value supported by reload register */ >>> +#define RLR_MAX GENMASK(11, 0) /* max value of reload register */ >>> /* IWDG_SR register bit mask */ >>> #define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ >>> @@ -55,15 +47,28 @@ >>> #define TIMEOUT_US 100000 >>> #define SLEEP_US 1000 >>> -#define HAS_PCLK true >>> +struct stm32_iwdg_data { >>> + bool has_pclk; >>> + u32 max_prescaler; >>> +}; >>> + >>> +static const struct stm32_iwdg_data stm32_iwdg_data = { >>> + .has_pclk = false, >>> + .max_prescaler = 256, >>> +}; >>> + >>> +static const struct stm32_iwdg_data stm32mp1_iwdg_data = { >>> + .has_pclk = true, >>> + .max_prescaler = 1024, >>> +}; >>> struct stm32_iwdg { >>> struct watchdog_device wdd; >>> + const struct stm32_iwdg_data *data; >>> void __iomem *regs; >>> struct clk *clk_lsi; >>> struct clk *clk_pclk; >>> unsigned int rate; >>> - bool has_pclk; >>> }; >>> static inline u32 reg_read(void __iomem *base, u32 reg) >>> @@ -80,21 +85,30 @@ static int stm32_iwdg_start(struct watchdog_device *wdd) >>> { >>> struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); >>> u32 val = FLAG_PVU | FLAG_RVU; >>> - u32 reload; >>> + u32 timeout, presc, iwdg_rlr, iwdg_pr; >>> int ret; >>> dev_dbg(wdd->parent, "%s\n", __func__); >>> - /* prescaler fixed to 256 */ >>> - reload = clamp_t(unsigned int, ((wdd->timeout * wdt->rate) / 256) - 1, >>> - RLR_MIN, RLR_MAX); >>> + timeout = clamp_t(unsigned int, wdd->timeout, >>> + wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); >>> + >>> + if (timeout != wdd->timeout) >>> + dev_warn(wdd->parent, "timeout skrinked to %d\n", timeout); >>> + >> >> Valid values for timeout should be set in the set_timeout function, >> not here. As such, there is no need for this warning. More specifically, >> if the selected timeout is between min_timeout and max_hw_heartbeat_ms, >> and the hardware can not meet the exact requested value, the set_timeout >> function should adjust wdd->timeout value accordingly. >> > > Ok, so I will adjust the timeout (with prescaler and reload look-up) > value in set_timeout function. thanks > >> Example: The requested timeout is 55 seconds, but the hardware can >> only support either 32 or 64 seconds. The set_timeout function should >> then set wdd->timeout to either 32 or 64. >> >> Furthermore, this is a valid condition. For example, the timeout could >> be set for one hour (or day), and the maximum heartbeat could be one >> minute. In that situation, the watchdog core handles heartbeat/ping >> requests. Again, this does not warrant a warning. >> >> On top of all that, if the hardware can not set a minimum timeout of >> 1 second, min_timeout should not be set to 1 second. It should be set >> to the actual minimum supportable value if that value is larger than >> 1 second. >> >>> + presc = DIV_ROUND_UP(timeout * wdt->rate, RLR_MAX + 1); >>> + >>> + /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ >>> + presc = roundup_pow_of_two(presc); >>> + iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; >>> + iwdg_rlr = ((timeout * wdt->rate) / presc) - 1; >>> /* enable write access */ >>> reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); >>> /* set prescaler & reload registers */ >>> - reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ >>> - reg_write(wdt->regs, IWDG_RLR, reload); >>> + reg_write(wdt->regs, IWDG_PR, iwdg_pr); >>> + reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); >>> reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); >>> /* wait for the registers to be updated (max 100ms) */ >>> @@ -150,7 +164,7 @@ static int stm32_iwdg_clk_init(struct platform_device *pdev, >>> } >>> /* optional peripheral clock */ >>> - if (wdt->has_pclk) { >>> + if (wdt->data->has_pclk) { >>> wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk"); >>> if (IS_ERR(wdt->clk_pclk)) { >>> dev_err(&pdev->dev, "Unable to get pclk clock\n"); >>> @@ -191,8 +205,8 @@ static const struct watchdog_ops stm32_iwdg_ops = { >>> }; >>> static const struct of_device_id stm32_iwdg_of_match[] = { >>> - { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK }, >>> - { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK }, >>> + { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, >>> + { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, >>> { /* end node */ } >>> }; >>> MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); >>> @@ -200,20 +214,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); >>> static int stm32_iwdg_probe(struct platform_device *pdev) >>> { >>> struct watchdog_device *wdd; >>> - const struct of_device_id *match; >>> struct stm32_iwdg *wdt; >>> struct resource *res; >>> int ret; >>> - match = of_match_device(stm32_iwdg_of_match, &pdev->dev); >>> - if (!match) >>> - return -ENODEV; >>> - >>> wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); >>> if (!wdt) >>> return -ENOMEM; >>> - wdt->has_pclk = match->data; >>> + wdt->data = of_device_get_match_data(&pdev->dev); >>> + if (!wdt->data) >>> + return -ENODEV; >>> /* This is the timer base. */ >>> res = platform_get_resource(pdev, IORESOURCE_MEM, 0); >>> @@ -231,8 +242,9 @@ static int stm32_iwdg_probe(struct platform_device *pdev) >>> wdd = &wdt->wdd; >>> wdd->info = &stm32_iwdg_info; >>> wdd->ops = &stm32_iwdg_ops; >>> - wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate; >>> - wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate; >>> + wdd->min_timeout = 1; >> >> Is this guaranteed to be no larger than 1 under all circumstances ? >> >> [ Not that the old code was necessarily correct - it might have set >> min_timeout to 0 if wdt->rate is high ] > > Infact, for not guaranteed the min timeout at 1s, the input clock > (wdt->rate) should be < at 12Hz. > > On ST micro controller/processor the wdt->rate is based on LSI > (Low Speed Internal) clock which is defined around 32KHz-39KHz > > I wanted avoid to set 0, due to min_timeout definition > ("unsigned int" in struct watchdog_device) and comparator used > in watchdog_timeout_invalid function. > > if the calculated value is < 1 => I could set 1, > else I round on UP or Down value? > The minimum is 1 second. Other than that, if you want to round it up or down is really your call. The easiest would probably be to use DIV_ROUND_UP(); that would take care of all situations. Thanks, Guenter > Regards, > Ludo > >> >>> + wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * >>> + 1000) / wdt->rate; >>> wdd->parent = &pdev->dev; >>> watchdog_set_drvdata(wdd, wdt); >>> -- >>> 2.7.4 >>> > ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-04-29 14:03 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-04-26 13:41 [PATCH] watchdog: stm32: add dynamic prescaler support Ludovic Barre 2019-04-26 14:16 ` Guenter Roeck 2019-04-29 13:51 ` Ludovic BARRE 2019-04-29 14:03 ` Guenter Roeck
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